TEMPORAL DISSOCIATION OF NEUROTENSIN NEUROMEDIN N MESSENGER-RNA EXPRESSION IN TOPOGRAPHICALLY SEPARATE SUBSETS OF RAT STRIATAL NEURONS FOLLOWING ADMINISTRATION OF HALOPERIDOL/

The expression of the neurotensin/neuromedin N gene in the rat caudate -putamen was studied at 7 and 24 h following the administration of hal operidol using a riboprobe and non-isotopic in situ hybridization hist ochemistry. As has been reported by others, expression of neurotensin/ neuromedin N mRNA in the dorsolateral quadrant of the caudate-putamen was undetectable in controls, robust at 7 h and minimally detectable a t 24 h following haloperidol administration. In the dorsomedial and ve ntrolateral quadrants of the caudate-putamen, barely detectable basal expression of neurotensin/neuromedin N mRNA observed in controls was c onspicuously enhanced at 24 h following administration of haloperidol both in terms of numbers of hybridized neurons, which were about 200% of. control values, and the amount of chromogen accumulated over indiv idual neurons. The data are consistent with at least two subpopulation s of caudate-putamen neurons in which neurotensin/neuromedin N mRNA ex pression is differentially regulated in response to haloperidol admini stration.